Update docs for Immutable and recursion on denormalize

Author: paularmstrong

docs/api.md

@@ -43,13 +43,15 @@ const normalizedData = normalize(myData, mySchema);
 
 ## `denormalize(input, schema, entities)`
 
-Denormalizes an input based on schema and provided entities. The reverse of `normalize`.
+Denormalizes an input based on schema and provided entities from a plain object or Immutable data. The reverse of `normalize`.
 
 *Special Note:* Be careful with denormalization. Prematurely reverting your data to large, nested objects could cause performance impacts in React (and other) applications.
 
+If your schema and data have recursive references, only the first instance of an entity will be given. Subsequent references will be returned as the `id` provided.
+
 * `input`: **required** The normalized result that should be *de-normalized*. Usually the same value that was given in the `result` key of the output of `normalize`.
 * `schema`: **required** A schema definition that was used to get the value for `input`.
-* `entities`: **required** An object, keyed by entity schema names that may appear in the denormalized output.
+* `entities`: **required** An object, keyed by entity schema names that may appear in the denormalized output. Also accepts an object with Immutable data.
 
 ### Usage